Essentials of Diagnosis
Rise of serum creatinine of ≥0.5 mg/dL or ≥25% baseline within 48 hours after parenteral contrast administration.
Peak in serum creatinine usually occurs within 3–5 days with complete resolution in 7–10 days for most patients.
Oliguria and need for dialysis are unusual and are primarily seen in patients with diabetes with severe chronic kidney disease (CKD).
Contrast-induced nephropathy (CIN) is a reversible form of nonoliguric acute kidney injury (AKI) brought about by iodinated contrast. It typically occurs within 24–48 hours after intravascular administration of contrast. Contrast-induced nephropathy is a common cause of AKI whose incidence is expected to grow as the population ages with more chronic kidney disease (CKD) along with an increased incidence of diabetes mellitus (DM). Observational retrospective studies have demonstrated that patients incurring CIN had significantly higher in-hospital and late mortality than counterparts who did not develop CIN, particularly so if they went on to need a dialysis. Multivariate regression analysis, adjusting for baseline differences in comorbidities, strongly suggests that CIN is, in fact, an independent predictor of mortality. Other observational studies suggest CIN may result in CKD or worsening of preexisting CKD.
There are a number of patient-related risk factors for the development of CIN of which the most important is that of underlying CKD. The majority of patients developing CIN have baseline CKD with higher incidences of CIN seen with more severe CKD. Another risk factor is that of DM, but only if this disease is present concomitantly with CKD. Patients with underlying CKD and DM are at the highest risk for the development of CIN and oliguric CIN. Patients with a similar magnitude of CKD without DM are at lower risk and DM without CKD is associated with minimal or no increased risk. Other risk factors for the development of CIN include congestive heart failure, older age, and a volume-depleted state all of which are probably markers for a low glomerular filtration rate. An additional risk factor may include the concurrent use of nephrotoxic agents, such as nonsteroidal anti-inflammatory drugs. Multiple myeloma has traditionally been considered a risk factor for CIN. However, recent studies using modern contrast agents indicate that patients with multiple myeloma are not at a greater risk, provided that they are volume replete at the time of contrast exposure.
Procedure-related factors will also influence the likelihood of CIN. Most studies suggest that exposure to larger volumes of parenteral contrast causes greater predisposition to CIN. A precise “safe” volume of contrast cannot be recommended since risk of CIN depends on multiple risk factors in addition to volume. Formulas to calculate low-risk volumes rely heavily on the magnitude of underlying CKD. In the past, choice of contrast media, specifically high-osmolar contrast media has been shown to increase CIN risk compared to low-osmolar or iso-osmolar contrast media. However, high-osmolar contrast media is no longer used for studies which ...